A radiation image such as an X-ray image has been widely applied in the medical field for diagnosing a disease. Specifically, a radiation image obtained in combination of an intensifying paper and a film has been improved to achieve a high sensitivity and a high image quality during a long period of history and as the result, it is still now being used in the medical field of the world as an imaging system having a high reliability and a high cost performance. Recently, a computed radiography (CR) employing a stimulable phosphor panel has been commercialized and the improvements in sensitivity and image quality have been further continued.
The above mentioned stimulable phosphor panel accumulates radiation passed through an object and then, with irradiating the phosphor panel with exciting light, the phosphor panel emits stimulated light of which strength is corresponding to the dosage of accumulated radiation. The stimulable phosphor panel contains a substrate having thereon a laminated stimurable phosphor. One of the examples of a production method of a stimurable phosphor panel is disclosed in Patent Document 1, in which a stimulable phosphor layer is formed on a substrate followed by a thermal treatment. (refer to paragraphs 0034 and 0035).
When a stimulable phosphor layer formed on a substrate is subjected to a thermal treatment as described in Patent Document 1, the moisture in the crystal of the stimulable phosphor is removed, resulting in an increase in the amount of light emitted from the stimulable phosphor. However, the emitting amount of the light is not fully increased only by conducting a heat treatment and it may be possible that the sharpness of the image is not fully enough or the luminance of the phosphor may be lowered.
Patent Document 1: Japanese Patent Publication Open to Public Inspection (hereafter referred to as JP-A) No. 2003-279696